Method of die preparation



Nov. 13, 1951 w. A. MARACZ 2,574,793

METHOD OF DIE PREPARATION Filed Aug. 5, 1948 [mentor V Patented Nov. 13, 1951 METHOD OF DIE PREPARATION William A. Maracz; Parma, Ohio, assignor to The American Steel and Wire Company of New Jersey, a corporation of New Jersey Application August 5, 1948, Serial No. 42,699

2 Claims.

-This invention relates to improved methods and apparatus for lapping and polishing wire drawing dies.

Commonly these dies comprise a metal holder and an insert of hard material, such as tungsten carbide. The latter contains a passage which includes a bearing and an entrance angle approach to the bearing and through which wire is drawn to reduce it to any desired size. The surfaces of the die passage are prepared for use first by lapping or ripping and finished by polishing. Usual lapping and polishing apparatus slowly rotates the die while applying a reciprocating and rapidly rotating tool to these surfaces. The tool works an abrasive suspension, such as diamond powder or boron carbide, over the surfaces to shape them as desired. In previous practice with which I am familiar, the tool has rotated either on the same axis as the die, or else on axes at various angles to the die axis. According to the present invention, I have found that lapping and polishing can be speeded and made more efficient by arranging the axis of rotation of the tool parallel to the axis of rotation of the die, but slightly eccentric thereto.

Therefore the principal object of the present invention is to provide improved methods and apparatus for lapping and polishing wire drawing dies in which these operations are conducted more efficiently by arranging the axes of rotation of the die and the tool parallel but slightly eccentric to each other.

In accomplishing this and other objects of the invention, I have provided improved details of structure, a preferred form of which is shown in the accompanying drawing, in which:

The single figure is a vertical sectional view of a wire drawing die and a portion of a lapping or polishing machine embodying features of the present invention.

Referring more in detail to the drawing:

There is shown at a wire drawing die which has the usual insert l2 of hard material such as tungsten carbide. The latter contains a passage which includes a bearing I3 and an entrance angle H, the surfaces of which are prepared by lapping and polishing.

For performing these operations the die is supported on a rotatable platform l5, which may be rotated slowly by any suitable mechanism, as known in the art. As indicated in the drawing, the die is free to shift laterally on said platform. A tool [6 for lapping or polishing the die surfaces is supported from above. The apparatus has mechanism for rapidly rotating said tool and reciprocating it axially, also as known in the art. A typical relation among these movements is for the die platform to rotate 2 to revolutions per minute, and the tool to rotate 10,000 revolutions per minute in the same or opposite direction and to reciprocate 1,000 strokes per minute.

In accordance with the present invention, the axis about which the tool rotates is parallel and eccentric to the axis a: about which the die rotates. The eccentricity may range from about 1 inch to about inch.

As already stated, the tool reciprocates axially. On its upstroke the tool is removed from the die surface and on its down stroke it re-engages this surface. In usual operation the point on the die surface which the tool re-engages is spaced arcuately from the point from which it has last been removed. Thus the tool point rides down the surface of the entrance angle on each down stroke and shifts the die relative to the platform in the direction indicated by the arrow in the figure and the die approaches a position of being centered about the tool axis. This additional motion between the tool and the die contributes effectively toward lapping or polishing the die surface, and hence improves the efficiency of these operations.

While I have shown and described only a single embodiment of the invention, it is apparent that modifications may arise. Therefore, I do not wish to be limited to the disclosure set forth but only by the scope of the appended claims.

I claim:

1. A method of lapping and polishing tapered passages in wire drawing dies comprising mounting a die on a support on which it is freely shiftable laterally, rotating the support, and alternately engaging and disengaging the tapered surface of the die passage with a rotating tool which has a tapered work engaging portion, the tapered portion of the tool having a smaller maximum diameter than the tapered passage in the die at any point at which the tool contacts said passage, the axes of rotation of the die support and of the tool being parallel, each engagement of the tool with the surface of the die passage shifting the die laterally on its support toward a position in which the die would be centered about the tool axis.

2. A method of lapping and polishing tapered passages in wire drawing dies comprising mounting a die on a support on which it is freely shiftable laterally, rotating the support, and alternately engaging and disengaging the tapered surface of the die passage with a rotating tool which has a tapered work engaging portion, the tapered portion of the tool having a smaller maximum diameter than the tapered passage in the die at any point where the tool contacts said passage, the axes of rotation of the die support and of the tool being parallel and offset ,4, to 1% inch, each engagement of the tool with the surface of the die passage shifting the die laterally on i'tsJsuppoi-t toward a position in which the die would be centered about the tool axis.

WILLIAM A. MARACZ.

REFERENCES CITED The following references are of record in the file of this patent:

5 UNITED STATES PATENTS Number Name Date 879,277 Landis Feb. 18, 1908 2;465,867 Gargano Mar. 29, 1949 

